The present invention relates to a semiconductor device and a process for manufacturing it and, more particularly, to a technique which is effective if applied for switching the functions and word structures of a memory module including a plurality of semiconductor devices.
According to our investigations, the memory module to be used as an extended memory in a personal computer or a work station is constructed by mounting, on a module wiring substrate, a memory or a DRAM (dynamic random access memory) semiconductor device, made of a SOJ (small outline package) type resin-sealed package, for example.
In order that the memory module may have specifications conforming to the device to be used, there is mounted on the aforementioned module wiring substrate a memory in which the functions are switched in the refresh cycle, such as a refreshing operation cycle or a reading mode, such as FAST PAGE or EDO (extended data out).
The switching of these functions of the memory is executed by connecting a predetermined electrode in a semiconductor chip through a bonding wire with a supply voltage Vcc or a ground potential Vss or no connection terminal (NC) in the bonding step for packaging.
As another method of switching the aforementioned memory functions, moreover, there is known both a memory for selecting a predetermined reading mode in dependence upon a predetermined signal fed from the outside of the memory, as disclosed in Japanese Patent Laid-Open No. 75494/1984, and a memory for designating a bit length mode programmably on the basis of a predetermined signal, as disclosed in Japanese Patent Laid-Open No. 59682/1986. On the other hand, a memory module also is disclosed in Japanese Patent Laid-Open No. 334112/1994.
Incidentally, a memory extended system of this kind is disclosed in detail, for example, on pp. 114 to 126 of "Semiconductor MOS Memory and Its Use", as issued on Aug. 30, 1990 by Nikkan Kogyo Shinbunsha and edited by Yasoji Suzuki. This publication describes the circuit construction and operations of a memory extending DRAM board.